update read_marker so receipts aren't sent to large rooms

Author: incognitobeeper

synapse/handlers/account_data.py

@@ -99,7 +99,12 @@ async def _notify_modules(
                 logger.exception("Failed to run module callback %s: %s", callback, e)
 
     async def add_account_data_to_room(
-        self, user_id: str, room_id: str, account_data_type: str, content: JsonDict
+        self,
+        user_id: str,
+        room_id: str,
+        account_data_type: str,
+        content: JsonDict,
+        notify_ephemeral: bool = True,
     ) -> int:
         """Add some account_data to a room for a user.
 
@@ -108,6 +113,7 @@ async def add_account_data_to_room(
             room_id: The room to add a tag for.
             account_data_type: The type of account_data to add.
             content: A json object to associate with the tag.
+            notify_ephemeral: Should ephemeral events be notified.
 
         Returns:
             The maximum stream ID.
@@ -116,6 +122,8 @@ async def add_account_data_to_room(
             max_stream_id = await self._store.add_account_data_to_room(
                 user_id, room_id, account_data_type, content
             )
+            if not notify_ephemeral:
+                return max_stream_id
 
             self._notifier.on_new_event(
                 StreamKeyType.ACCOUNT_DATA, max_stream_id, users=[user_id]
@@ -125,12 +133,15 @@ async def add_account_data_to_room(
 
             return max_stream_id
         else:
+            # TODO: beeper - work out how to test this? is only one instance supported?
+            # https://github.com/beeper/synapse/blob/14f26a62d45f7de100070f3ae54b311a69200022/synapse/config/workers.py#L60
             response = await self._add_room_data_client(
                 instance_name=random.choice(self._account_data_writers),
                 user_id=user_id,
                 room_id=room_id,
                 account_data_type=account_data_type,
                 content=content,
+                notify_ephemeral=notify_ephemeral
             )
             return response["max_stream_id"]
 

synapse/handlers/read_marker.py

@@ -15,6 +15,7 @@
 import logging
 from typing import TYPE_CHECKING, Optional
 
+from synapse.api.constants import RECEIPTS_MAX_ROOM_SIZE
 from synapse.types import JsonDict
 from synapse.util.async_helpers import Linearizer
 
@@ -58,8 +59,11 @@ async def received_client_read_marker(
                     event_id, existing_read_marker["event_id"]
                 )
 
+            num_users = await self.store.get_number_joined_users_in_room(room_id)
+            should_send_reciepts = num_users <= RECEIPTS_MAX_ROOM_SIZE
+
             if should_update:
                 content = {"event_id": event_id, **(extra_content or {})}
                 await self.account_data_handler.add_account_data_to_room(
-                    user_id, room_id, "m.fully_read", content
+                    user_id, room_id, "m.fully_read", content, notify_ephemeral=should_send_reciepts
                 )

tests/rest/client/test_sync.py

@@ -530,6 +530,31 @@ def test_read_receipt_not_sent_to_large_rooms(self) -> None:
             # Test that we didn't get a read receipt.
             self.assertIsNone(self._get_read_receipt())
 
+    def test_read_marker_doesnt_send_receipt_to_large_rooms(self) -> None:
+        # Beeper: we don't send read receipts on rooms with over 100 users
+        # add another 100 users to the room
+        for i in range(RECEIPTS_MAX_ROOM_SIZE):
+            user = self.register_user(f"user_{i}", f"secure_password_{i}")
+            tok = self.login(f"user_{i}", f"secure_password_{i}")
+            self.helper.join(room=self.room_id, user=user, tok=tok)
+
+        for receipt_type in (ReceiptTypes.FULLY_READ, ReceiptTypes.READ_PRIVATE):
+            res = self.helper.send(
+                self.room_id, body="woah, this is a big room!", tok=self.tok
+            )
+
+            # Send a read receipt
+            channel = self.make_request(
+                "POST",
+                f"/rooms/{self.room_id}/read_markers",
+                {receipt_type: res["event_id"]},
+                access_token=self.tok2,
+            )
+
+            self.assertEqual(channel.code, 200, channel.json_body)
+            # Test that we didn't get a read receipt.
+            self.assertIsNone(self._get_read_receipt())
+
     def _get_read_receipt(self) -> Optional[JsonDict]:
         """Syncs and returns the read receipt."""